Created in 1967, French Regional Natural Parks (RNPs) can be considered to be early test cases for sustainable development. Various initiatives dedicated to promoting local development and drawing benefits from the improved status of sustainably-managed areas have been implemented in the RNPs, including a policy of trademarking local products and services. In this connection, the RNPs have been the object of renewed international interest and are held up as a possible management model, especially for countries of the global South. We study the impacts of this RNP trademark policy on local sustainability, building on the example of the Grands-Causses RNP, which is a rural mid-altitude territory in the South of France. Because of the analytical framework we use, namely that of the economics of proximity, we focus on the social dimension of sustainable development, and more specifically on the questions of collective action and stakeholder coordination. This approach makes it possible for us to identify key factors for the success of this kind of policy, and for its transferability to other contexts, particularly in developing countries.